Tape guides are employed to define a desired tape path within various tape transport system components, such as data storage tape cartridges, tape drives, etc. To this end, data storage tape cartridges have been used for decades in the computer, audio, and video fields. Due to their low cost and high storage capacity, data storage tape cartridges continue to be an extremely popular form of recording large volumes of information for subsequent retrieval and use.
One type of data storage tape cartridge consists generally of an outer shell, or housing, maintaining two tape reels, two or more discrete corner guides, and a length of magnetic storage tape. The storage tape is wrapped about and extends between the two tape reels. The separate corner guides, in turn, articulate the storage tape through a defined tape path. In this regard, the tape path typically extends across a head access window (or a read/write zone) formed in the housing. In particular, the corner guides are positioned at opposite sides of the head access window to direct the tape path through the head access window. These two corner guides are typically “compliant guides,” each providing an arcuate guide surface and opposing tape edge (or lateral) stop surfaces, one of which is compliant. Any remaining corner guides or guide surfaces are positioned to direct the storage tape between the tape reels and the corner guides associated with the head access window. In addition, a door is normally associated with the head access window to provide selective access to the storage tape. With a single reel cartridge design, the storage tape is extended between the cartridge reel and a tape drive take-up reel along a tape path defined, at least in part, by one or more tape guides within the tape drive.
During use, the data storage tape cartridge is inserted into a tape drive. With a dual reel cartridge, the door is maneuvered into an open position and a transducer, such as a magnetic read/write head, engages the storage tape via the head access window. Alternatively, with a single reel design, the storage tape is driven from the cartridge and into the drive for interaction with the read/write head. Regardless, to ensure consistent, accurate engagement by the read/write head, the storage tape must be precisely positioned.
Various inherent design issues may compromise the desired, precise positioning of the storage tape across the read/write head. For example, the tape reel(s) may contribute to unexpected lateral (or edge-to-edge) tape movement. In this regard, the typical tape reel includes a central hub and opposing flanges. The storage tape is wrapped about the central hub and is laterally constrained by the hub flanges (i.e., the hub flanges limit lateral movement of the storage tape by contacting a respective top or bottom edge of the tape). However, to avoid contact with the storage tape edges, a slight opening taper to the hub flanges is provided. That is to say, an overall lateral spacing between the opposing flanges is greater than a width of the storage tape, typically on the order of 0.002-0.02 inch. As a result, during tape reel rotation, the storage tape may move laterally from flange to flange by as much as 500 micrometers. This is especially true during the data transfer mode in which the outermost layers of the storage tape are normally not tightly wrapped about the tape reel hub. In this case, a “slack” is developed in the storage tape, such that the storage tape easily moves laterally between the opposing flanges. This undesired lateral tape movement is “seen” by the head, leading to read/write errors.
The corner guides described above cannot readily correct undesired lateral tape movement. As previously described, the compliant tape guides typically incorporate opposing, transverse surfaces that redirect lateral tape movement. Consequently, lateral motion at the tape reel(s) can cause lateral motion at the read/write head because the complaint guide acts as a fulcrum for the tape path.
Any slight deviation, or lateral movement, from a desired planar position of the storage tape within the head access window can result in read/write errors. If the storage tape is slightly above or below an expected location, the read/write head will experience difficulty in finding a desired track on the storage tape. Additionally, the read/write head can encounter tracking problems where the head “loses” a desired track. Finally, recent improvements in storage tape media have increased the available track densities on the storage media, and subsequent lateral movements of the storage tape during the read/write process can result in increased read/write errors. Unfortunately, attempts to incorporate multiple, spaced tape guides within the cartridge and/or the tape drive so as to effectuate offset edge control have been less than successful due to unacceptable tape buckling along the unsupported span of storage tape between the distinct, spaced guides.
While the evolution of tape transport systems, including cartridge and tape drive components, has greatly improved performance, other concerns, including lateral tape movement, remain. Therefore, a need exists for a tape guide for use in a tape transport system, such as a data storage tape cartridge and/or a tape drive, configured to control lateral tape movement with minimal edge wear.